Tadpoles may Help in Maintaining Ecosystem of Freshwater Streams

Tadpoles, larva of a frog or a toad, may help in maintaining the ecosystem of freshwater streams, according to a new study.

Researcher Katrin Schmidt, a Ph.D. candidate at James Cook University, Australia, studied the role of tadpoles in nature. There has been a significant decline in the population of amphibians across the globe. Various factors have been attributed to the population loss of the species; in particular, much of the decline has been linked to the fungal disease chytridiomycosis.

In the Australian Wet Tropics, various amphibians, including stream-breeding frogs from undisturbed upland rainforest areas, have either declined or disappeared.

"Stream-breeding frogs are important in linking streams and the surrounding riparian landscape," Schmidt said. "By acting both as consumers and prey to other species they contribute to energy transfer within and between the two habitats."

The loss of tadpoles could affect the ecosystem of freshwater streams as well as aquatic organisms, as tadpoles could play a significant role in maintaining the structure and function of streams through their feeding activities and their interactions with other animals, Schmidt said.

Despite its role in maintaining streams through feeding, the feeding ecology of tadpoles is not understood well, she said. There is not much known about the tadpoles' main source of energy and nutrients. By analyzing the isotope signatures and possible food sources in streams, Schmidt hopes to determine how tadpoles are interlinked in the food web.

Tadpoles also benefit microbes like algae and other aquatic animals by providing nutrients. During leaf litter breakdown, tadpoles and some other invertebrates might interact with each other to get nutrients.

Leaf litter is the main source of energy in forest streams. When animals feed on leaves, nutrients get released. "Nutrients released as a result of tadpole activity can benefit microorganisms, algae and other animals, but the extent of this is not known," Schmidt said.